2014 2-speed transfer case - faint whine when in AUTO or 4Hi

[Charlie207]

Finally got some snow the other day and noticed that when I twisted the transfer case selector into AUTO or 4HI I could hear a faint whine after a few seconds. It occurred on a flat dry road at ~40mph and would go away as soon as I twisted it back into 2WD. IIRC, the front differential and driveshafts are always spinning, so the noise would be from inside ther transfer case?

The front diff fluid was checked in Oct, and the shop said it was fine. I don't remember off the top of my head if they checked the transfer case, but I assume they didn't leave it empty if they found it that way.

I don't remember a faint whine when in AUTO or 4Hi in the past. Any thoughts?

 

[Geotrash]

Finally got some snow the other day and noticed that when I twisted the transfer case selector into AUTO or 4HI I could hear a faint whine after a few seconds. It occurred on a flat dry road at ~40mph and would go away as soon as I twisted it back into 2WD. IIRC, the front differential and driveshafts are always spinning, so the noise would be from inside ther transfer case?

The front diff fluid was checked in Oct, and the shop said it was fine. I don't remember off the top of my head if they checked the transfer case, but I assume they didn't leave it empty if they found it that way.

I don't remember a faint whine when in AUTO or 4Hi in the past. Any thoughts?

This exact thing happened with my '02 Suburban. Over time it progressed to a howl in 4wd. The problem was worn bearings in the front diff. I had a local driveline shop rebuild it to the tune of $1200, or so.

 

[Charlie207]

(replied in other post)

 

[Charlie207]

This exact thing happened with my '02 Suburban. Over time it progressed to a howl in 4wd. The problem was worn bearings in the front diff. I had a local driveline shop rebuild it to the tune of $1200, or so.

(not liked)

Curious...

Why would the front diff bearings go bad if they are always turning? Everything from the output shaft of the transfer case to the hubs are always spinning in 2wd, yes?

 

[B-train]

Not exactly. There is an actuator in the front differential that engages the gears when 4wdnis selected. The axles, bearings will spin. Driveshaft will not. This is with a selectable 2wd/4wd case setup.

 

[Charlie207]

Not exactly. There is an actuator in the front differential that engages the gears when 4wdnis selected. The axles, bearings will spin. Driveshaft will not. This is with a selectable 2wd/4wd case setup.

Can a failing 4wd/front diff actuator cause partial engagement, so that 4wd still works, but the front gears might not be fully engaged? Or, is it an all-or-nothing function?

 

[Charlie207]

Also found this video that explained my knowledge-gap in the front diff 4wd actuator:

 

[Geotrash]

Also found this video that explained my knowledge-gap in the front diff 4wd actuator:

A little V1agra should fix that thermal style one.

 

[89Suburban]

Also found this video that explained my knowledge-gap in the front diff 4wd actuator:

This guy has a very good breakdown and explanation video too for the front diff.